btrfs-progs: Check the csum tree node before go through the csum tree

[BUG]
Some fsfuzzed btrfs image will cause btrfsck segfault.

[REPRODUCER]
Run btrfsck on a csum tree block corrupted image.

[REASON]
check_csums() function call btrfs_search_slot() on csum_tree but doesn't
check whether the csum_tree contains a valid extent_buffer, which causes
the segfault.

[FIX]
Check the csum_root->node before any search.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/cmds-check.c b/cmds-check.c
index 4c01330..23dbd0a 100644 (file)
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -3867,6 +3867,10 @@ static int check_csums(struct btrfs_root *root)
        unsigned long leaf_offset;
 
        root = root->fs_info->csum_root;
+       if (!extent_buffer_uptodate(root->node)) {
+               fprintf(stderr, "No valid csum tree found\n");
+               return -ENOENT;
+       }
 
        key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
        key.type = BTRFS_EXTENT_CSUM_KEY;